埋藏岩溶洞穴垮塌深度定量图版及其在碳酸盐岩缝洞型储层地质评价预测中的意义

通过对岩溶洞穴垮塌的岩石力学原理及塔里木盆地奥陶系实钻资料的分析,基本明确了洞穴埋藏垮塌的控制因素是岩石抗弯强度、洞穴尺度、洞穴距风化暴露面的距离等,并得到了洞穴垮塌深度的定量图版。该图版对于钻前预测现今埋藏于地下的碳酸盐岩洞穴是否已经垮塌、洞穴埋藏演化史精确恢复以及对裂缝—洞穴型储层的评价预测具有较强的实践意义。

A Quantitative Plate of Collapsed Karst Cave Depth and Its Application in Geological Prediction and Evaluation of Carbonate Reservoir

Karst caves are the significant feature in carbonate rocks. To determine whether a reservoirs develop or not in and around karstic caves,it is a key to know the existence of buried collapses under overlying load. The principle of rock mechanics for indicates that the buried collapses of karst caves are under control of three key parameters,i.e. the anti-bending strength of rock,the cave scale and the distance of a cave away from the exposed weathering surface. According to this principle,quantitative formulas and a plate of buried collapse depth of karst cave are obtained. Actual drilling data from Ordovician limestone caves in Tarim Basin prove the correctness of this conclusion and the plates of buried collapse depth can be applied in forecasting of collapsed caves present underground,an accurate burial evolution history of caves and evaluation of carbonate fractured-caved reservoirs.